Ball valves typically include a valve body that includes a plurality of ports. A valve member carried within the valve body selectively directs fluid between selected ones of the ports based upon the selected orientation of the valve member relative to the valve body. The valve member directs fluid through the ball valve via a passage in the valve member that can be selectively aligned with certain ones of the plurality of ports, thereby creating a fluid flow passage. The valve is said to be in the “open” position when the passage of the valve member is selectively aligned with one port and any number of the remaining ports. The valve is said to be in the “closed” position when the passage of the valve member is out of alignment with all of the ports.
Ball valves also typically require the use of seals at each of the ports of the valve member within the valve body. The seals function to prevent fluid flow around the valve member, thereby restricting all fluid flow to the passage of the valve member. However, valve seals can leak and allow undesired fluid flow when the valve is in the closed position due to machining tolerances of the valve body, valve seals, and valve member. Furthermore, ball valves can deform or shift under large pressure differentials, also causing the seals to leak.
To overcome these problems, valve seals are often designed to dynamically adjust to compensate for different pressure loads and machining tolerances via the use of dynamic seals. Dynamic seals often incorporate a pressure plate that is biased against the valve seal under the action of a spring. Typically, one end of the spring contacts the pressure plate, while another end of the spring is compressed by tightening a fitting installed in the port that is in line with the seal. Unfortunately, the end of the spring in contact with the pressure plate move off of center of the pressure plate during assembly and/or operation. When the spring is off of center, the pressure plate imparts an unbalanced load on the valve member. When the pressure load upon the valve member is unbalanced, the valve member will impart an undesirable torque upon a valve stem of the ball valve. This can lead to leakage at the valve stem, or stress fractures within the stem.
Moreover, in multi-port applications, one port typically allows flow along an axis that is transverse to two inline ports, such as in a three way valve. If the valve member is biased out of centered alignment with the inline ports, a leak path may be generated between the valve member and one or more of the dynamic seals.
Additionally, in certain types of ball valves, the valve body may also house a flow disk. The flow disk operates to characterize the flow through the ball valve as the ball valve transitions between open and closed conditions. The flow disk characterizes the flow through the ball valve by introducing any number of geometrical obstructions generally normal to the direction of fluid flow through any open fluid flow passage of the ball valve. As the ball valve is rotated between the open and closed states, the inclusion of a flow disk causes the flow passage through the valve member to align with a different shaped aperture through the flow disk than was present without the flow disk at the same angular orientation. Thus, the flow disks recharacterize the flow of the fluid at a given angular orientation of the ball valve. Typically, the pressure plate and flow disk are concentric with one another, and adjacently aligned at a port within the valve body.
Unfortunately, current fluid flow disks may freely rotate within the valve body about their central axis. Therefore, in order for the flow disk to provide a repeatable characterization of the flow through the valve, the flow disk must be designed to offer the same characterization regardless of its angular rotation. This design constraint limits the types of flow governance a flow disk can offer. Alternatively, painstaking measures must be taken during assembly to assure the proper orientation of the flow disk. Further yet, a large force must be applied to the flow disk to create sufficient friction to prevent angular rotation thereof.
Embodiments of the present invention relate to improvement over the current state of the art.